Oxygen delivery and apnea

To the Editor:We read with great interest the article by Zagol et al.1 Like

the authors, we also have noted that blood transfusions forpremature infants with high frequencies of apnea can de-crease the apnea. We recall that, as stated in the article byZagol et al, the probability that subsequent apnea will occurvaries depending on the hematocrit. Moreover, it was indeedmost interesting that the authors discussed the effectivenessof blood transfusion on apnea using the rigorous detectionof apnea with continuous electronic waveform analysis. Re-fsum et al reported that “with very premature infants, bymeans of blood transfusion, the majority of [hemoglobin]HbF is replaced by HbA, but subsequently, this is graduallyreplaced by HbF, and by the projected delivery date, the per-centage of HbA is small, and the capacity of HbA is low.”2

Moreover, De Halleux et al reported that “when 26.9mL/kg of blood is transfused in very premature infants, theamount of HbF drops to below half (92.9% � 1.1% vs42.6% � 5.7%), and subsequent to blood transfusion, thePO2 under the same oxygen saturation (SpO2 50%), increases(18.5� 0.8 mmHg vs 21.0� 1 mm Hg).”3 Therefore, one ofthe reasons that apnea improves with blood transfusion isthat the percentage of HbA increases, which shifts the oxygendissociation curve to the right. As a result, more oxygen issupplied to the central nervous system, which may decreaseapnea. If the blood transfusion amounts and hematocritvalues for the blood transfusions for apnea are available,that information would be useful.

Jun-ichi Nakashima, MDAtsushi Ohashi, MD, PhD

Kazunari Kaneko, MD, PhDDepartment of PediatricsKansai Medical UniversityHirakata-shi, Osaka, Japan

http://dx.doi.org/10.1016/j.jpeds.2012.12.005

References

1. Zagol K, Lake DE, Vergales B, MoormanME, Paget-Brown A, Lee H, et al.

Anemia, apnea of prematurity, and blood transfusions. J Pediatr 2012;

161:417-21.

2. Refsum HE, Bechensteen AG, Lindemann R. Shift from fetal to adult he-

moglobin production in a preterm infant after exchange transfusion:

a quantitative approach. Pediatr Hematol Oncol 1998;15:431-5.

3. De Halleux V, Truttmann A, Gagnon C, Bard H. The effect of blood

transfusion on the hemoglobin oxygen dissociation curve of very early

preterm infants during the first week of life. Semin Perinatol 2002;6:

411-5.

Reply

To the Editor:We appreciate the comments from Nakashima et al. Their

speculations about a possible relationship between respiratorydrive andhematocrit or hemoglobin levels before and after thetransfusion certainly are reasonable in that there is a well-de-scribed inverse relationship in neonates between paO2 and re-spiratory depression, as mentioned in our article and thepreviously described study.1 The data in Figure 3 of our article,which show a clear decrease in the probability of apnea withincreasing hematocrit, regardless of postmenstrual age, alsoare consistent with that hypothesis and could be a reflectionof decreasing fetal hemoglobin, as speculated by Nakashimaet al. Unfortunately, because this study was a retrospectiveone, and our neonatal intensive care unit does not have a pro-tocol for when to transfuse a patient (ie, it is left up to thediscretion of the attending physician), we do not havesufficiently timed pre- and posttransfusion blood studies toadequately investigate the hypothesis. Such a prospectivestudy, in which investigators used our continuous physiologicmonitoring algorithms and perhaps included measurementsof fetal hemoglobin, certainly would be of interest.

Kelley Zagol Kovatis, MDJohn Kattwinkel, MD

Neonatology/PediatricsUniversity of Virginia Medical Center

Charlottesville, Virginiahttp://dx.doi.org/10.1016/j.jpeds.2012.12.012

Reference

1. Darnall RA, Ariagno RL, Kinney HC. The late preterm infant and the con-

trol of breathing, sleep and brainstem development: A review. Clinics in

Perinatology 2006;33:883-914.

CORRECTION

In the article, “Parenteral Nutrition of Preterm Infants with a Lipid Emulsion Containing 10% Fish Oil: Effect onPlasma Lipids and Long-Chain Polyunsaturated Fatty Acids,” by D’Ascenzo et al, J Pediatr 2011;159:33-8, the authorsinadvertently provided the incorrect middle name for the seventh author, whose full name should have been listed asPaola Elisa Cogo, MD, PhD.

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